feat: add category field to housekeeping tasks + TechnicalPage for maintenance tasks

- Add migration 025 to add `category` column (housekeeping/maintenance) to housekeeping_tasks
- Backend: filter by ?category= in GET, store category in POST, allow patching category
- API client: HkPayload + housekeeping.list() now support category param
- HousekeepingPage: filters by category=housekeeping so maintenance tasks don't appear
- RoomContextMenu: priority sub-form for dirty/cleaning status, tech task creation inline form
- BookingCalendar: accepts onMaintenanceTaskCreate prop, passes priority to onRoomUpdate
- CalendarPage: handleRoomUpdate creates task for dirty+cleaning (with priority), new handleMaintenanceTaskCreate for category=maintenance tasks
- TechnicalPage: new page for viewing/creating/updating maintenance tasks
- App.tsx: /technical route added
- Sidebar: Тех. задачи nav item added under Управление

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

backend/migrations/025_task_category.sql

@@ -0,0 +1,6 @@
+ALTER TABLE housekeeping_tasks
+  ADD COLUMN IF NOT EXISTS category VARCHAR(20) NOT NULL DEFAULT 'housekeeping';
+
+-- Index for faster filtering
+CREATE INDEX IF NOT EXISTS housekeeping_tasks_category_idx
+  ON housekeeping_tasks(hotel_id, category, created_at DESC);